text: When a blood vessel ruptures or gets injured, factor VII comes into contact with tissue factors which starts a process called the blood coagulation cascade. Its purpose is to stop bleeding and repair tissue damage. When this process is too active due to various problems the risk of blood clots or embolisms increases. As the name indicates the cascade is a multi-step procedure where the main product thrombin is made by activating various proenzymes (mainly serine proteases) in each step of the cascade. Thrombin has multiple purposes, but mainly it converts soluble fibrinogen to an insoluble fibrin complex. Furthermore, it activates factors V, VIII and XI, all by cleaving the sequences GlyGlyGlyValArg-GlyPro and PhePheSerAlaArg-GlyHis, selectively between Arginine (Arg) and Glycine (Gly). These factors generate more thrombin. Thrombin also activates factor XIII that stabilizes the fibrin complex and therefore the clot and it stimulates platelets, which help with the coagulation. Given this broad action of thrombin it stands as a good drug target for anticoagulant drugs such as heparin, warfarin and DTIs and antiplatelet drugs like aspirin.